Bittersweet
by World'sOnlyConsultingTimeLady
Summary: Genos bakes a cake and hopes for the best as he jumps to conclusions about Saitama's admirer, while Saitama just misinterprets everything. A Valentine's Day one-shot. Better description on AO3. Unapologetic genosai.


**Inspired by AoT Junior High Volume 4, which was read while Pride and Prejudice played in the background. Note to self: don't combine those two things while obsessed over these ridiculous lovebirds. Somehow, it made this sprawling thing.**

* * *

The idea of getting Saitama something for Valentine's Day first presented itself to Genos by an overly amorous fan girl who wanted to get ahead of his other admirers and give him chocolate three weeks before Valentine's Day. Glancing through her letter, the cyborg is mildly annoyed by her tenacity. Not only is she certain that she loves him the most, she also believes herself entitled to his affections. Within the letter, among other things, is her contact information, as well as her schedule for the week of the holiday.

 _I know you'll love me too,_ she gushes underneath her schedule, _and I know you'll want to surprise me as a thank-you, so here is my schedule. I would prefer you surprise me when I am out with my friends (you would also get to show me off, which few have been able to do), but should you drop by while I am alone, that wouldn't be terrible either. I know of many ways we could entertain ourselves. ;)_

Genos glances at Saitama apprehensively, hearing his sensei snort in derision. A strange fear overwhelms the cyborg, and, strangely, he doesn't want Saitama to see her message. His teacher, however, isn't paying any attention to Genos; he is staring at his own letter, which is marked with heavy red ink. The cyborg feels himself inching closer before he can stop himself, his body humming as he prepares to incinerate the offensive letter. He didn't care how annoyed Saitama would be at the cyborg for wasting his energy on a stupid hate message; he can't help himself.

"Huh," Saitama mutters, and Genos catches the word "love." _Love_.

'Sensei deserves adoration,' Genos thinks as he ignores the bitter taste in his mouth, the way he feels strangely breathless. There must be something wrong with him; first, he shouldn't feel so terribly about other people seeing what Genos sees in his master, and secondly, he shouldn't be feeling sensations he is almost incapable of. Food doesn't lack taste, but there isn't anything Genos particularly likes or dislikes; therefore, he shouldn't be like this, hating the taste of this bitter jealousy, hating the taste of chocolate overwhelming his thoughts. 'Other people should love sensei. He deserves some good after all the terrible things they've done to him. I shouldn't be so selfish.'

"You have an admirer, Saitama-sensei." Genos doesn't like that his voice wavers like it's a question, like he's asking whether or not he will be replaced, but there's nothing he can do, so he looks away from his teacher to the disgusting letter in his hands. An awkward silence passes, and he can't help but look up, away from the letter. He is shocked to see his teacher staring at the girl's obnoxious message with a strange, cold expression.

"As do you," Saitama comments, pouting like he always does whenever Genos' fan club surfaces in their apartment, the iciness not quite absent from his lips, his eyes.

They were both thankful that no one had appeared in their apartment in person yet. Genos would've incinerated anyone, regardless of who they were or which hero they came to taunt or admire; in the very least, he might have restrained himself barely only if Saitama requested, but if they proved to be after Saitama in any way, shape, or form...

"You okay? You look like you're going to be sick." Before Genos can reply, Saitama's nose scrunches up ever-so-slightly (and adorably). He raises his free hand. "If you're going to throw up, go to the bathroom and do it."

Genos shakes his head, amused by his teacher's behavior. "I'm not going to throw up, sensei. I don't have a stomach."

"Oh. Right." Saitama scratches his head sheepishly.

The cyborg wants to continue talking, to reassure Saitama, but he knows that prolonged conversation is disliked by his teacher. It won't comfort him like he wants to, so he opts for silence.

Genos' gaze falls away from him slowly, lingering pathetically on his shoulders, his arms, his hands—that damned letter, with "love" written on it, nowhere near the bottom of the page. If he squints, Genos can see the word in other places, but he can't trust that his mind isn't tricking him.

"Is it the chocolate?"

Genos tilts his head. "What?"

"The chocolate, from one of your fan club people, is that why you looked so repulsed? You don't like chocolate?"

"I don't care for chocolate—but that's not what displeased me."

"Is it 'cause it's a ridiculously early Valentine's Day gift?"

Genos frowns; surely Saitama-sensei doesn't actually want to hear the full reason. His teacher's annoyance with lengthy monologues is something Genos is thankful for. He nods slightly, slowly. "The romantic affection we receive from fans bothers me."

He is surprised to see a small smile on Saitama's face as he glances down at the letter in his hands, flushes, and folds it carefully. "Any chocolate you get, I'll eat, if you'd like. I doubt my fans are going to send me chocolate." He chuckles. "For all their love, they don't know that they're sending chocolate to the wrong guy."

Before Genos can process what just happened, his teacher stands up, his disinterested expression tinted with lingering amusement, makes a comment about an important errand, and dashes out of their apartment.

He stares after his teacher for a little while, pondering the random excursion before remembering what Saitama said.

 _I doubt my fans are going to send me chocolate._

Genos frowns. Sensei deserves better than that. He deserves chocolate.

* * *

It is surprisingly easy for Genos to smuggle supplies for chocolate into their apartment. Once he did the appropriate research, both online with recipes and watching which chocolates his teacher preferred, he became more confident about his plans. The only good thing about Genos' fan girls and their affection is that they sent a wide range of chocolate, and it is perfect for Genos to observe Saitama's preferences. It was difficult at first to discern whether or not he actually enjoyed the chocolate; he scowled at the boxes, chewed on the chocolates with a strange vehemence that didn't make sense to Genos, and smiled a little only if he liked it. Genos had to watch his teacher closely, but eventually, he gets the information he needs.

He's found that Saitama likes plain dark chocolate the best. Genos overheard him mutter about preferring a cake instead while the cyborg was in the hall of their apartment, so he decides to make him a dark chocolate cake.

It has been two weeks. A part of Genos wants to wait until the proper day to present Saitama with his gift, but the implications are too damning. Of course, he wants to tell him how he feels, and he will with the cake, but doing it on Valentine's Day is cheesy and makes him feel like he has no control over the situation.

If he gives the cake to him then, Genos feels like he is more likely to repulse his sensei, or, worse, make him feel like Genos only did it out of pity. The chances of these emotions being strongly expressed or felt seem lower if he does it earlier. He knows he can't play it off as something unrelated to Valentines day—Saitama is too clever, Genos too bad a liar, and he does want his teacher to know his thought process behind it. No matter how badly things go.

Saitama deserves to know that he is loved and cherished by someone with enough personal information and experience to have these feelings deeply.

It is a blessing and a curse that his teacher has suddenly taken to random trips where he either returns disappointed and empty-handed or loaded with groceries and an air of forced nonchalance, like he'd spent most of the time somewhere else, and only stopped to pick up groceries at a sale to hide the true reasons for his absence. Much as the cyborg wants to investigate, he respects his privacy.

Besides, there's only one reason Saitama would do something like this so close to Valentine's Day, and Genos doesn't want to see his teacher shopping for someone else, looking at the stupid holiday items and wondering whether his love interest would like it. Genos can't stop remembering that red letter, can't stop remembering the fond look on Saitama's face as he read it.

This morning, Genos sees something that almost makes him stop his plans altogether, as today is the day he plans to bake the cake, but he presses on despite all warning signs begging him not to.

Last night, before bed, Genos notices Saitama handling an object carefully. His back is to the cyborg, so he doesn't see what he is doing until his teacher walks away and gets into his futon, sleepily murmuring a goodnight. When he is sure he is asleep, Genos looks and sees an empty vase on the table. It is simple, pretty without being overly ornate. Genos loves it, and he almost vocalizes his thoughts when he realizes that it is tied to the mysterious outings somehow. It is obvious to him that Saitama bought it, because no fan would get him something so simple (no one knew him well enough to know what he liked, not like Genos), nor would any one they both knew. If it was a friend that bought him the vase, Saitama would've said something.

Something clenches in Genos, and he wants to do something, but he doesn't know what. He is unable to sleep for hours afterwards.

When the vase is filled with flowers the next morning, Genos understands that it is a gift for someone, and that someone is important to Saitama romantically. Saitama is nowhere to be found, as usual, so Genos sighs wistfully and drags himself into the kitchen. He said he was going to make the cake, and nothing is going to stop him.

Genos sighs and looks at his finished cake. He conceals it as best he can from his teacher, who is still out on his mysterious excursions, and ignores the rising anxiety. He is going to give it to Saitama tomorrow, no matter what. He is going to tell him about his feelings, and they have never felt so potent, so noticeable until he tries to plan how he will tell his teacher. They seem so natural when he's not thinking about them like this; he hadn't even noticed how his feelings shifted until one night, during a movie, he'd heard Saitama laugh, and all he wanted to do was freeze the moment, live in it forever. That, or kiss him.

Genos didn't have an internal crisis when he realized this. He just dealt with it, showing his affection as quietly and unobtrusively as possible, but he couldn't keep pretending like he didn't care deeply for his teacher. Not when people were so terrible to him, not when—

There's a loud thump against the door that sounds a little like a punch. Genos hears the crumpling of paper, then awkward shuffling.

The door opens; Genos is so distracted by his confusion that he doesn't sense Saitama coming to the apartment until he interrupted his thoughts and entered, carrying grocery bags on his arms, and in his hands, scraps of paper crumpled in his right, a chocolate cake, clearly not store-bought. It's a gift from someone who loves Saitama, who knew him well enough to get him a cake instead of a simple chocolate bar. Someone who took time out of their day to make it for him.

Genos wants to be happy that someone clearly cares about him, but he also wants to crawl into a hole and die. His gift feels worthless now, and he doesn't know what to do.

"Genos?" Saitama's unpacking the groceries, clearly a little confused that his disciple hasn't stepped up to help him like usual; he obviously sees that there is something wrong, but he doesn't know how to acknowledge it. "Look, someone left me a cake. We can eat it after dinner if you want." Genos doesn't reply, too focused on the cake, trying to understand why his teacher wants to share a love-gift with _him_. The silence is awkward, and apparently Saitama feels the same way, because he hovers after putting everything away, staring at him with a puzzled expression that quickly morphs to understanding. "Oh... I'm sorry, Genos. I completely forgot. You don't like chocolate."

"It's okay, sensei. It's obviously a gift meant for you; it would be wrong of me to eat it, anyways."

Saitama taps the cover of the cake lightly. "I don't think they'd mind," he comments, clearly with the intention of placating him, even if he doesn't like the cake, but it has the opposite affect. Genos couldn't be more ruffled; it is another blatant reminder that there is someone _else_.

Genos turns away. "What do you want for dinner tonight?"

Instead of a proper response, there is the sound of Saitama's socked feet padding towards him. Genos senses a hand hovering awkwardly over his shoulder, hesitating before decisively patting him. His hand is warm, his movements soothing. "I'm not in the mood for anything in particular. I can make us dinner a little later."

Genos doesn't feel the need to eat, so he doesn't argue. He relaxes inadvertently as his hand stops moving and rests on him. There is a strange pause, and Genos savers the seconds of peaceful affection, the sensation of his hand, capable of so much destruction, nearly caressing him. He feels alive, and he wants to vocalize this, but he remembers the other cake, the strange letter, and he keeps quiet.

He makes up his mind to pack his things while his teacher is out of the apartment; with another in his life, Saitama won't need a cyborg hell-bent on revenge anymore, and his presence certainly won't be appreciated once he confesses his weakness. Besides, he needs to keep moving, to find the thing that ruined his life. Once that is complete, he can fight monsters until he dies.

Saitama's hand falls away, brushing lightly against his arm. He smiles at the cyborg and moves past him to sit in front of the TV. After a moment, Genos follows, indulging his urges by sitting as close as he can to him without drawing attention to himself.

* * *

All is well until Saitama goes to make them dinner.

Genos relaxes too much as he watches with him, focuses too little on his surroundings until it is too late, until the familiar sounds of Saitama making dinner fade into unnatural silence. He is shaking when he gets up, and he knows before he sees that Saitama has found the cake.

When he enters the room, he is surprised to see a hint of anger on Saitama's face. "I didn't think you were the type, Genos." His voice is cold, and he won't meet Genos' eyes.

"What type?" Everything is shaking; this isn't how it was supposed to happen. He is supposed to present him with the cake and blurt that he loves him, or something else. Only in his worst imaginings was Saitama livid; he didn't think his affection so horrible. He is clearly very wrong.

Saitama taps the container, leaving a small dent. "I didn't think you liked _that_."

Genos crosses his arms. "I don't see what's wrong with _that_."

Saitama looks at him, finally, but he's glaring, and Genos feels the strange urge to scream. "I didn't think you were that desperate. I thought you were better than that. I thought you knew how wrong it is."

"Wrong because the idea of me, a weak cyborg, loving someone is incomprehensible to you? Wrong because you think my affections—"

"No! No!" Saitama waves his hands, almost comically, save the anger in his voice, his face. "It's wrong because she's just some stalker, Genos. You don't love fans who send you schedules or chocolate or tell you they love you when they don't even know you. The Genos I know isn't so cheap with his 'affection.'"

"The Genos _you_ know?" Instantly, Genos knows of the girl he is referencing, and vaguely he understands the weird sounds at the door, the pieces of paper that quickly vanished as he put away the food. He is insulted that his teacher is so blind, so impulsive, that he thinks so little of his disciple. "You barely know me," he snarls, darting for the door. Saitama has ruined everything. "If you actually did, you'd know that that cake is for _you_. Because I love _you_."

He can't stand to be with Saitama, not after that. Even if he misunderstood the person Genos is interested in, the words hurt, and he couldn't bear to hear them repeated, this time without any misunderstanding about who his love is. It takes everything in him to not incinerate something, and he vaguely tries to reassure himself that everything will be okay, that he will leave and go back to the original mission. That Saitama's anger will fade, like everything else of his related to Genos. That Saitama will forget about him after a while, distracted by the other person in his life.

This is the wrong thing to think. All control is lost, and Genos incinerates the floor beneath him; he falls down, his fires fading as he lands on the charred remains of the level below.

"Genos!" Saitama is shouting his name again and again as he leaps into the hole and lands beside him. He wobbles on his feet before stumbling over to Genos. He holds out a hand, and when the cyborg flinches away, Saitama's hand wavers uncertainly for a minute before being retracted quickly. "I would never hurt you intentionally, Genos. I'm sorry."

"I don't need your pity," Genos snarls, waiting for his limbs to wake up so he can get out.

"I don't pity you! I regret that I jumped to conclusions, but what else was I supposed to do? She put some stupid note on the door about her plans for Valentine's Day, including a party, and then I find a cake you clearly made hidden away." Saitama huffs. "I didn't mean to belittle your feelings for me, but why would I assume that you liked me?"

Genos looks away, vaguely feeling his legs slowly regain sensation. He twitches, and Saitama seems to realize his intentions, because his eyes widen and he crouches in front of him.

"Genos. Please, listen to me."

Genos sees that he will not be able to flee without getting past Saitama. "I don't want to hear it." His voice is wavering like he is about to cry. "I've seen the signs; I know you have someone else in your life. I don't want to interrupt that. I just wanted to get it off of my chest before I left. I wanted to be more graceful about it, and I didn't want to shout it angrily, but I couldn't help it. It doesn't matter to me that you don't like me back; I just want you to be happy, and I felt wrong concealing my true feelings from you, and—"

"Genos," Saitama interrupts, not unkindly. "Twenty words or less."

"I love you. You have someone else. I wanted to tell you so I could leave without regrets."

Saitama tilts his head, confused. "I don't have someone else?"

"What about your cake, that letter, the flowers?"

Saitama flushes and scratches his neck with one hand. "The first two were from my mom. The flowers were for you. You don't like chocolate, and I've seen the way you eye the flower stand by that one supermarket. The stand moved away from that store, so I had to run around looking for it, but I found it."

"...Oh."

Genos is staring at Saitama, wide-eyed, and Saitama won't meet his eyes. Genos should be overwhelmingly mortified, but he takes in the blush, his admission about the flowers, the extreme anger, and he understands his underlying message.

 _Sensei_.

Genos' limbs are fully functional now, and he wastes no more time, his arms reaching up to pull Saitama down. His teacher allows this control, allows Genos' lips to find his. The kiss is gentle for a few seconds, but then Saitama deepens it. His arms wrap around Genos, pulling him into a sitting position, pulling him closer. His hands are on Genos' hips, Genos' hands on Saitama's face, and they continue to kiss until Saitama pulls away to breathe.

Genos tugs him close again, this time pressing a kiss to his cheek before hugging him tightly. Saitama's breathing is heavy and ragged as he reciprocates the embrace.

"I'm sorry, sensei," Genos murmurs.

One of Saitama's hands travels up from his hips to fiddle with his hair. "I'm sorry too, Genos. We were both idiots."

"The flowers are beautiful."

"Thank you." Genos can hear Saitama's grin in his voice. "Your cake looks really good."

"Thank you," Genos parrots.

"Are you going to leave?"

Genos sighs. "Only if you ask me to."

Saitama's grip tightens, and Genos knows his answer. He reciprocates, his hands clutching him closer as he runs his hands soothingly up and down his teacher's back.

They get up an hour later, both men grinning. When they get back to their apartment, Saitama eats some of Genos' cake and praises his cooking skills, genuinely humming in approval as he eats the dessert before dinner.

When Genos pulls him in for another kiss after the second slice, elated by Saitama's approval, he finds that chocolate only tastes good when he's kissing his sensei.

* * *

 **(I'm not used to writing in present tense, so if I messed up, please let me know so I can fix it.)**

 **Thank you for reading!**


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